Hypothalamic dysfunction involves the region of the brain called the hypothalamus. This area is located behind the eyes and helps control the pituitary gland, particularly in response to stress. The pituitary in turn controls the thyroid, adrenal glands, ovaries, and testes.

The hypothalamus also helps regulate weight and appetite, body temperature, salt and water balance, and emotions. It is also involved in growth, milk production, childbirth, and sleep.

Causes of hypothalamic dysfunction include tumors (growths), surgery, radiation, infections and inflammation, genetic disorders, head trauma, bleeding, malnutrition, and excess iron. The most common tumors in the area are craniopharyngiomas in children.

Anorexia (excessive voluntary weight loss) and bulimia (vomiting induced to reduce weight) can also cause hypothalamic dysfunction.

If a tumor is present, there may be headaches or loss of vision. Symptoms generally relate to the hormones that are missing. In children, there may be growth problems -- either too much growth or too little -- or puberty that occurs too early or too late.

Hypothyroidism may occur, causing fatigue, cold intolerance, weight gain, and hair or skin changes. Menstrual disturbance, impotence, breast enlargement, and loss of body hair and muscle (in men) may occur. Low adrenal function may cause dizziness and weakness. Less commonly, patients may also experience obesity, body temperature disturbance, emotional abnormalities, excessive thirst, or uncontrolled urination.

A variant of hypothalamic dysfunction that occurs in men, called Kallmann's syndrome, includes hypogonadism (lowered function of sexual hormones) and an inability to smell.

Blood or urine tests will be done to determine levels of hormones such as thyroid, prolactin, cortisol, estrogen, testosterone, and growth hormone. Pituitary hormones will be checked and are usually easier to measure than are hypothalamic hormones.

Specialized tests may be needed, including hormone injections followed by timed blood samples. If a tumor is present, an eye test called a visual field exam may be done. MRI or CT scans may be done to image the brain.